diff --git a/app/assets/javascripts/workers/worker_world.js b/app/assets/javascripts/workers/worker_world.js
index a1c4baf0f..3dcae25d2 100644
--- a/app/assets/javascripts/workers/worker_world.js
+++ b/app/assets/javascripts/workers/worker_world.js
@@ -289,6 +289,7 @@ self.setupDebugWorldToRunUntilFrame = function (args) {
             return;
         }
         Math.random = self.debugWorld.rand.randf;  // so user code is predictable
+        Aether.replaceBuiltin("Math", Math);
     }
     self.debugWorld.totalFrames = args.frame; //hack to work around error checking
     self.currentDebugWorldFrame = args.frame;
@@ -343,6 +344,7 @@ self.runWorld = function runWorld(args) {
     return;
   }
   Math.random = self.world.rand.randf;  // so user code is predictable
+  Aether.replaceBuiltin("Math", Math);
   self.postMessage({type: 'start-load-frames'});
   self.world.loadFrames(self.onWorldLoaded, self.onWorldError, self.onWorldLoadProgress);
 };
diff --git a/app/lib/Angel.coffee b/app/lib/Angel.coffee
index fbdb252db..aae10c724 100644
--- a/app/lib/Angel.coffee
+++ b/app/lib/Angel.coffee
@@ -211,6 +211,7 @@ module.exports = class Angel extends CocoClass
   doSimulateWorld: (work) ->
     work.t1 = now()
     Math.random = work.testWorld.rand.randf  # so user code is predictable
+    Aether.replaceBuiltin("Math", Math)
     i = 0
     while i < work.testWorld.totalFrames
       frame = work.testWorld.getFrame i++
diff --git a/app/lib/surface/CocoSprite.coffee b/app/lib/surface/CocoSprite.coffee
index 882383b97..183d6aa65 100644
--- a/app/lib/surface/CocoSprite.coffee
+++ b/app/lib/surface/CocoSprite.coffee
@@ -100,6 +100,7 @@ module.exports = CocoSprite = class CocoSprite extends CocoClass
         @actions = @thangType.getActions()
         @buildFromSpriteSheet result
         @createMarks()
+        @queueAction 'idle'
 
   finishSetup: ->
     @updateBaseScale()
diff --git a/app/models/CocoModel.coffee b/app/models/CocoModel.coffee
index 515bbfa57..3a8838b65 100644
--- a/app/models/CocoModel.coffee
+++ b/app/models/CocoModel.coffee
@@ -32,10 +32,12 @@ class CocoModel extends Backbone.Model
 
   onError: ->
     @loading = false
+    @jqxhr = null
 
   onLoaded: ->
     @loaded = true
     @loading = false
+    @jqxhr = null
     @markToRevert()
     @loadFromBackup()
 
@@ -91,6 +93,7 @@ class CocoModel extends Backbone.Model
     @jqxhr
 
   markToRevert: ->
+    return unless @saveBackups
     if @type() is 'ThangType'
       @_revertAttributes = _.clone @attributes  # No deep clones for these!
     else
@@ -104,7 +107,7 @@ class CocoModel extends Backbone.Model
     storage.remove @id
 
   hasLocalChanges: ->
-    not _.isEqual @attributes, @_revertAttributes
+    @_revertAttributes and not _.isEqual @attributes, @_revertAttributes
 
   cloneNewMinorVersion: ->
     newData = _.clone @attributes
diff --git a/app/models/SuperModel.coffee b/app/models/SuperModel.coffee
index 90118faa5..c5a4eeb55 100644
--- a/app/models/SuperModel.coffee
+++ b/app/models/SuperModel.coffee
@@ -169,9 +169,9 @@ module.exports = class SuperModel extends Backbone.Model
     _.defer @updateProgress
     r.clean()
 
-  onResourceFailed: (source) ->
+  onResourceFailed: (r) ->
     return unless @resources[r.rid]
-    @trigger('failed', source)
+    @trigger('failed', resource: r)
     r.clean()
 
   updateProgress: =>
@@ -216,14 +216,14 @@ class Resource extends Backbone.Model
 
   markFailed: ->
     return if @isLoaded
-    @trigger('failed', {resource: @})
+    @trigger('failed', @)
     @isLoaded = @isLoading = false
     @isFailed = true
 
   markLoading: ->
     @isLoaded = @isFailed = false
     @isLoading = true
-    
+
   clean: ->
     # request objects get rather large. Clean them up after the request is finished.
     @jqxhr = null
diff --git a/app/models/ThangType.coffee b/app/models/ThangType.coffee
index e1ccf1054..84fd8e713 100644
--- a/app/models/ThangType.coffee
+++ b/app/models/ThangType.coffee
@@ -159,7 +159,7 @@ module.exports = class ThangType extends CocoModel
     spriteSheet = @builder.build()
     @logBuild @t0, false, @options.portraitOnly
     @spriteSheets[key] = spriteSheet
-    delete @building[key]
+    @building[key] = false
     @builder = null
     @options = null
     spriteSheet
@@ -171,7 +171,7 @@ module.exports = class ThangType extends CocoModel
     buildQueue[0].t0 = new Date().getTime() if buildQueue[0]
     buildQueue[0]?.buildAsync()
     @spriteSheets[key] = e.target.spriteSheet
-    delete @building[key]
+    @building[key] = false
     @trigger 'build-complete', {key:key, thangType:@}
     @vectorParser = null
 
diff --git a/app/schemas/models/user.coffee b/app/schemas/models/user.coffee
index a6525bf91..5b4a93ca7 100644
--- a/app/schemas/models/user.coffee
+++ b/app/schemas/models/user.coffee
@@ -60,7 +60,7 @@ UserSchema = c.object {},
     colorConfig: c.object {additionalProperties: c.colorConfig()}
 
   aceConfig: c.object {},
-    language: {type: 'string', 'default': 'javascript', 'enum': ['javascript', 'coffeescript', 'clojure', 'lua', 'python', 'io']}
+    language: {type: 'string', 'default': 'javascript', 'enum': ['javascript', 'coffeescript', 'python', 'clojure', 'lua', 'io']}
     keyBindings: {type: 'string', 'default': 'default', 'enum': ['default', 'vim', 'emacs']}
     invisibles: {type: 'boolean', 'default': false}
     indentGuides: {type: 'boolean', 'default': false}
diff --git a/app/views/editor/article/home.coffee b/app/views/editor/article/home.coffee
index 41d7419f9..c34640d55 100644
--- a/app/views/editor/article/home.coffee
+++ b/app/views/editor/article/home.coffee
@@ -6,3 +6,12 @@ module.exports = class ThangTypeHomeView extends SearchView
   model: require 'models/Article'
   modelURL: '/db/article'
   tableTemplate: require 'templates/editor/article/table'
+
+  getRenderData: ->
+    context = super()
+    context.currentEditor = 'editor.article_title'
+    context.currentNew = 'editor.new_article_title'
+    context.currentNewSignup = 'editor.new_article_title_login'
+    context.currentSearch = 'editor.article_search_title'
+    @$el.i18n()
+    context
diff --git a/app/views/editor/level/home.coffee b/app/views/editor/level/home.coffee
index 247c9d3ff..ae31fd6e8 100644
--- a/app/views/editor/level/home.coffee
+++ b/app/views/editor/level/home.coffee
@@ -6,3 +6,12 @@ module.exports = class EditorSearchView extends SearchView
   model: require 'models/Level'
   modelURL: '/db/level'
   tableTemplate: require 'templates/editor/level/table'
+
+  getRenderData: ->
+    context = super()
+    context.currentEditor = 'editor.level_title'
+    context.currentNew = 'editor.new_level_title'
+    context.currentNewSignup = 'editor.new_level_title_login'
+    context.currentSearch = 'editor.level_search_title'
+    @$el.i18n()
+    context
diff --git a/app/views/editor/level/thangs_tab_view.coffee b/app/views/editor/level/thangs_tab_view.coffee
index 5d5cdd7b3..b675fd3bc 100644
--- a/app/views/editor/level/thangs_tab_view.coffee
+++ b/app/views/editor/level/thangs_tab_view.coffee
@@ -69,7 +69,7 @@ module.exports = class ThangsTabView extends View
     @level = options.level
 
     $(document).bind 'contextmenu', @preventDefaultContextMenu
-    
+
   getRenderData: (context={}) ->
     context = super(context)
     return context unless @supermodel.finished()
@@ -102,7 +102,7 @@ module.exports = class ThangsTabView extends View
       $('#thangs-list').height(oldHeight - thangsHeaderHeight - 40)
     else
       $('#thangs-list').height(oldHeight - thangsHeaderHeight - 80)
-      
+
 
   afterRender: ->
     super()
@@ -440,18 +440,15 @@ module.exports = class ThangsTabView extends View
 
   onDuplicateClicked: (e) ->
     $('#contextmenu').hide()
-    if !@addThangType
-      thang = @selectedExtantThang.spriteName
-      e.target = $(".add-thang-palette-icon[data-thang-type='" + thang + "']").get 0
-    @selectAddThang e
-    
+    @selectAddThangType @selectedExtantThang.spriteName, @selectedExtantThang
+
   toggleThangsContainer: (e) ->
     $('#all-thangs').toggle()
-    
+
   toggleThangsPalette: (e) ->
     $('#add-thangs-column').toggle()
     @onWindowResize e
-   
+
 
 class ThangsNode extends TreemaNode.nodeMap.array
   valueClass: 'treema-array-replacement'
diff --git a/app/views/editor/patches_view.coffee b/app/views/editor/patches_view.coffee
index 17aef667b..a75e1e36d 100644
--- a/app/views/editor/patches_view.coffee
+++ b/app/views/editor/patches_view.coffee
@@ -46,6 +46,7 @@ module.exports = class PatchesView extends CocoView
     @reloadPatches()
 
   reloadPatches: ->
+    @supermodel.resetProgress()
     @load()
     @render()
 
diff --git a/app/views/editor/thang/home.coffee b/app/views/editor/thang/home.coffee
index 2fb208723..1f585b2ab 100644
--- a/app/views/editor/thang/home.coffee
+++ b/app/views/editor/thang/home.coffee
@@ -5,10 +5,19 @@ module.exports = class ThangTypeHomeView extends SearchView
   modelLabel: 'Thang Type'
   model: require 'models/ThangType'
   modelURL: '/db/thang.type'
-  tableTemplate: require 'templates/editor/thang/table' 
+  tableTemplate: require 'templates/editor/thang/table'
+
+  getRenderData: ->
+    context = super()
+    context.currentEditor = 'editor.thang_title'
+    context.currentNew = 'editor.new_thang_title'
+    context.currentNewSignup = 'editor.new_thang_title_login'
+    context.currentSearch = 'editor.thang_search_title'
+    @$el.i18n()
+    context
 
   onSearchChange: =>
     super()
     @$el.find("img").error(-> $(this).hide())
 
-  # TODO: do the new thing on click, not just enter
\ No newline at end of file
+  # TODO: do the new thing on click, not just enter
diff --git a/app/views/kinds/SearchView.coffee b/app/views/kinds/SearchView.coffee
index 209abdd8e..6619a71c3 100644
--- a/app/views/kinds/SearchView.coffee
+++ b/app/views/kinds/SearchView.coffee
@@ -26,27 +26,6 @@ module.exports = class SearchView extends View
     'shown.bs.modal #new-model-modal': 'focusOnName'
     'hidden.bs.modal #new-model-modal': 'onModalHidden'
 
-  getRenderData: ->
-    context = super()
-    switch @modelLabel
-      when 'Level'
-        context.currentEditor = 'editor.level_title'
-        context.currentNew = 'editor.new_level_title'
-        context.currentNewSignup = 'editor.new_level_title_login'
-        context.currentSearch = 'editor.level_search_title'
-      when 'Thang Type'
-        context.currentEditor = 'editor.thang_title'
-        context.currentNew = 'editor.new_thang_title'
-        context.currentNewSignup = 'editor.new_thang_title_login'
-        context.currentSearch = 'editor.thang_search_title'
-      when 'Article'
-        context.currentEditor = 'editor.article_title'
-        context.currentNew = 'editor.new_article_title'
-        context.currentNewSignup = 'editor.new_article_title_login'
-        context.currentSearch = 'editor.article_search_title'
-    @$el.i18n()
-    context
-
   constructor: (options) ->
     @runSearch = _.debounce(@runSearch, 500)
     super options
diff --git a/app/views/play/level/tome/spell_view.coffee b/app/views/play/level/tome/spell_view.coffee
index 04851959e..9933033d0 100644
--- a/app/views/play/level/tome/spell_view.coffee
+++ b/app/views/play/level/tome/spell_view.coffee
@@ -18,9 +18,9 @@ module.exports = class SpellView extends View
   editModes:
     'javascript': 'ace/mode/javascript'
     'coffeescript': 'ace/mode/coffee'
+    'python': 'ace/mode/python'
     'clojure': 'ace/mode/clojure'
     'lua': 'ace/mode/lua'
-    'python': 'ace/mode/python'
     'io': 'ace/mode/text'
 
   keyBindings:
diff --git a/headless_client/worker_world.coffee b/headless_client/worker_world.coffee
index e40317bfe..667481858 100644
--- a/headless_client/worker_world.coffee
+++ b/headless_client/worker_world.coffee
@@ -91,6 +91,7 @@ work = () ->
       self.onWorldError error
       return
     Math.random = self.world.rand.randf # so user code is predictable
+    Aether.replaceBuiltin("Math", Math)
     console.log "Loading frames."
 
     self.postMessage type: "start-load-frames"